One-pot efficient synthesis of novel fused pentacyclic indolopyridobenzimidazoles and pyridoimidazopyridoindoles from the reaction of pyranoindolones with 1,2-diaminobenzenes and 2,3-diaminopyridines
摘要
The synthesis of a number of novel, fully conjugated, planar pentacyclic 5H-indolo[3鈥?2鈥?4,5]pyrido[1,2-a][1,3]benzimidazoles (ong class="boldFont">8ong>) and 11H-pyrido[3鈥?2鈥?4鈥?5鈥瞉imidazo[1鈥?2鈥?1,6]pyrido[3,4-b]indoles (ong class="boldFont">12ong>) by a one-pot reaction of pyranoindolones with substituted o-phenylenediamines or 2,3-diaminopyridines is described. In the case of 2,3-diaminopyridines the reaction proceeds regioselectively affording only regioisomers ong class="boldFont">12ong>. Structural assignments of the new compounds as well as complete assignment of 1H and聽13C NMR signals were based on the analysis of their 1H and 13C NMR (1D and 2D), IR, MS and elemental analysis data. Plausible mechanisms are proposed.